Behind the ethical message of blood in the jewish notion and in the law of holiness in Leviticus we have the ancient, archaic idea that blood is seat of the human soul or life force.
The core ethical message of blood was that blood was the essence of life, its vitality and energy, which has to be devoted to serving as offering (korban) under the altar to God (Hashem as they call God) and its consequence that under this leading sign the best of human life, its vitality and energy, should be also devoted in humilty into the right direction, namely to god (life belongs only under the altar, namely as offering for god).
This ethical core thought is an interesting though and acceptable moral idea per se. Also because blood is not seen under the altar as "sacrifice", "ransom", or "payment for guilts" although it might have been used in such circumstances, but only as "offering"/"gift". Therefore the human blood of Jesus could in jewish notion never pay for adamic sins in a real "ransom" scenario, but only serve as "offering" at most. Paul must have been used the word "ransom" as metaphor i think.
This ethical core thought that blood is lifeforce could however lead to the conclusion that in jewish eyes "blood was" always "sacred" and not only in the moment of killing an animal.
These notions developped on the basis of the jewish shy from contact with blood. Blood was for the Israelites not merely used as a methaphor or symbol of life but they had ...brrrr.... great shy of contacting it. This is the archaic story behind blood with the blood rites uuuuh and menstruation blood uuuuuhhhh, today we know that not everything what the old folks spoke is to hold and search for a double meaning, deeper sense, namely also for the idea that life or lifeforce or the divine principle is actually seated in the blood, a lifeforce which is of divine origin and therefore belonged to God.
Today the JW are confused and trouble their head about this old idea and make of it a STARK NONSENSE.